Strong and weak electrolytes

Strong and Weak Electrolytes: Definition, Explanation, and Examples

In chemistry, particularly in electrochemistry, electrolytes are substances that produce ions when dissolved in water, thereby conducting electricity. Based on how completely they ionize in solution, electrolytes are categorized into two main types: strong electrolytes and weak electrolytes.

What are Strong Electrolytes?

A strong electrolyte is a substance that completely dissociates into ions in aqueous solution. This means that almost all of the dissolved solute exists in the ionic form, allowing the solution to conduct electricity very efficiently.

Examples of strong electrolytes:

• Strong acids: HCl, HNO₃, H₂SO₄
• Strong bases: NaOH, KOH
• Soluble salts: NaCl, KBr, Ba(NO₃)₂

For instance, sodium chloride (NaCl) undergoes complete dissociation into its ions when it is dissolved in water:

NaCl (aq) → Na⁺ (aq) + Cl⁻ (aq)

What are Weak Electrolytes?

A weak electrolyte is a substance that partially ionizes in aqueous solution. In the case of weak electrolytes, only a limited amount of the solute ionizes, with the majority remaining in molecular form. Consequently, these solutions conduct electricity inefficiently.

Examples of weak electrolytes:

• Weak acids: CH₃COOH (acetic acid), H₂CO₃
• Weak bases: NH₃ (ammonia), C₅H₅N (pyridine)

For instance, acetic acid dissociates only partially in water:

CH₃COOH ⇌ CH₃COO⁻ + H⁺

The double arrow (⇌) signifies that the ionization process is reversible and does not go to completion.

Key Differences Between Strong and Weak Electrolytes

Understanding the difference between strong and weak electrolytes is crucial in solving problems related to conductance, pH, electrolysis, and equilibrium — all important topics in the JEE syllabus.